In the field of silviculture it is often necessary to eliminate weed trees to allow sunlight and nutrients to permeate the crop trees. In the past, forest workers have eliminated these undesirable weed trees by felling them with chainsaws or by applying herbicides. Both of these techniques have serious limitations. Felling of weed trees often results in damage to surrounding crop trees which defeats the purpose of the procedure. Moreover, felled trees may sprout and regrow over time. The injection of herbicides into notches cut in weed trees with a hatchet is a more effective method of eradication, but it can have a deleterious effect on forest wildlife, especially if the water table is contaminated.
It has been recognized that girdling is a more effective method of killing undesirable trees. This involves cutting a circumferential groove around the tree deeper than the cambium layer of growth to interrupt the flow of water and nutrients. Various hand and power driven tree girdlers are known in the prior art. For example, U.S. Pat. No. 2,792,670 issued 21 May, 1957 to Haynes; U.S. Pat. No. 3,158,956 issued 1 December, 1964 to Gudmundsen; and U.S. Pat. No. 4,996,773 issued 5 March, 1991 to Albertson; all relate to tree girdlers having motorized cutting blades. Such motorized tools are relatively cumbersome and are not suitable for safe use in very dense forests or on steep inclines. Further, chainsaws and other motorized blades have a tendency to cut too deeply, which may cause the girdled tree to topple when subjected to high winds, thus damaging adjacent crop trees. As indicated above, toppled trees may also sprout and regrow over time.
Heretofore, manually driven tree girdling tools have also suffered from significant shortcomings. Generally, such tools have been unable to achieve a deep enough cut and have resulted in tremendous worker fatigue because of their poor leverage design. Other hand-held tree girdlers have proven to be ineffective since they require too much work area around each tree to operate the tool effectively, thus rendering the tool ineffective in dense forest. The tools described in U.S. Pat. No. 3,090,159 issued 21 May, 1963 to Wimberley; and U.S. Pat. No. 4,236,306 issued 2 December, 1980 to Vrendenburg, have limitations in terms of their ability to completely sever the cambium layer, as they do not account for the fact that trees are not perfectly cylindrical. Additionally, such tools require two-handed operation which contributes to unsafe working conditions when on steep grades or uneven terrain.
Accordingly, the need has arisen for a compact, hand-held tool for efficiently girdling trees of varying diameter.